Routes of Radon Gas Entry

Could You Have Radon Gas in Your Home?

We often picture dust and fumes when we think of indoor air pollution because they’re either visible or have a strong odor.  But what about the invisible, odorless gas called radon that’s naturally occurring in the ground beneath many of our homes?  According to the US Environmental Protection Agency (USEPA), radon gas is the second leading cause of lung cancer in the US today.  In fact, only smoking causes more lung cancer deaths.  

I've been researching this topic for a long time now because both houses I've owned have had radon at different levels.  Read on to learn more about where radon gas can be found, its dangers, how to find out if radon is in your home (including my preferred method), and how to reduce the amount of it in your home.


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What Is Radon Gas and Where Is It Found?

Radon is a radioactive gas that is formed from the breakdown of natural uranium deposits in soil and rock.  The gas travels upward through the ground and seeps into homes through cracks and other gaps in the foundation.  In indoor air, concentrations are generally highest in the lowest level of the house. 

Radon gas has been found at high levels in every state.  On this map published by the USEPA, the areas with higher radon levels are shown in red and lowest levels in yellow, with orange areas falling in between.  

Map of Radon Zones in US

What Are the Dangers?

Radon gas is the leading cause of lung cancer in non-smokers, and the second leading cause of lung cancer in smokers.  It’s estimated that more than 20,000 people die in the US each year from lung cancer caused by radon gas.  Smokers that are also exposed to radon gas have a much higher chance of getting lung cancer.

In 2005, the US Surgeon General issued a national health advisory to warn people about the risks of breathing indoor air containing radon gas and to urge people to take steps to prevent it from seeping into their homes. 

USEPA recommends taking action to decrease radon levels in the home if it is detected at 4 picocuries per liter of air (pCi/L) or more.  EPA also recommends that people consider taking action if radon is between 2 and 4 pCi/L in indoor air.   According to USEPA estimates, one in every 15 homes nationwide has a radon level at or above 4 pCi/L. 

Testing for Radon Gas in Your Home

Testing for radon in your home is critical since it can’t be detected by sight or odor, and there are no immediate symptoms that would indicate its presence.  A radon test should always be conducted before you buy a home so that the cost for fixing the issue can be negotiated as part of the sale. You should also test for radon if you’re living in a home that hasn’t been tested recently.  

Radon testing should be repeated every two years because conditions can change over time.  The amount of radon in your home can also change drastically from season to season. Concentrations are typically the highest in colder months for a couple of reasons: 1) windows are generally closed so fresh air is limited, and 2) the furnace creates a pressure differential that can draw gas from below the foundation and into the home.

There are several options available for testing you home.

Home Test Kits

Radon test kits are simple to use and can be purchased at home improvement stores or through online testing companies.  You set the test kit in the lowest level of the house that you spend your time in, and leave it out for a specified amount of time.  Once that time is up, you put the test kit in a pre-labelled, pre-paid envelope for shipment back to the laboratory.  Many companies will provide results on the same day that they receive the sample in the mail.  I've used Radon Testing Corporation of America in the past, but many others are available as well.  This type of testing generally costs between $15-$25 per sample.

Digital Air Meter

This is my personal favorite because I love being up close and personal with the quality of air in my home.  With a digital meter, you have the freedom to test for radon on every level of your house during different seasons.  This is especially important if you’ve had a borderline reading in the past and want to monitor whether it’s stable or increasing.  It is also incredibly useful if you have a radon mitigation system and you want to be sure that it's working properly.

These will run you about $149, so the up-front investment is a little higher than the home test kits.  To me it was completely worth the extra money for the peace of mind of being able to continuously monitor during different times of the year and in different rooms of the house.  I have a test going on right now in the basement to check that the radon mitigation system is still effective.  I'm planning to move it up one floor every two days to check the levels throughout the house.

The radon meter that I’ve always used and absolutely love is the Safety Siren Pro Series 3 Radon Gas Detector.  I’ve used it at both of my houses, both of which have had 2 pCi/L or higher of radon in the basement level.  When I first bought it, I compared the results from the meter to home test kit samples that I set side by side.  I found the results to be very close to one another, which adds to my confidence in the results.  

Safety Siren Pro Series 3 Radon Gas Detector

Professional Testing

If you’re purchasing a home, most home inspectors will collect the radon sample as part of their services.  Other companies offer radon testing as well as mitigation services if the results are high. A list of certified radon professionals can be found at the National Radon Proficiency Program website and the National Radon Safety Board website.

Lowering Radon Gas Levels

What if you take your test and find that radon in your home is higher than you’d like to see, let’s say more than 4 pCi/L?  While this isn't the best news, the positive side is that radon levels can be lowered through tried and true solutions.  You’ll want to hire a contractor to assess the best method for reducing levels in your home, and installing the appropriate mitigation system.  Refer to the links above to find a certified contractor in your area.  

Different contractors will have different ideas on how to install a system to best suit your home’s structure and foundation type.  It’s worth the time to get a quote from more than one contractor so that you can compare pricing and get a better feel for the options available.  

I've included a short description of the more common types of radon mitigation below.  

Subslab Depressurization

Generally the most effective solution to reduce radon in your home is to install a subslab depressurization system.  This involves installing one or more vertical pipes through the floor slab and into the crushed stone or soil beneath the slab.  A fan draws radon gas from beneath your floor slab and vents it outside above your roof line.

Subslab Depressurization System

Image from USEPA

Sealing Cracks

Another measure that is typically taken in conjunction with subslab depressurization is to seal gaps and cracks in your foundation.  This helps to reduce the amount of radon that can seep into the home, and also makes the subslab depressurization system more effective.  Sealing up cracks and gaps is not sufficient to take care of the problem on its own, since new cracks can develop, and the sealants may eventually wear out.

Crawl Spaces

If you have a crawl space, the most common method for radon mitigation is to install thick plastic sheeting over the dirt floor in the crawl space and vent it.  The membrane serves as a barrier that captures the vapor coming up from the ground.  A suction pipe is installed beneath the membrane, and a fan draws the vapor from beneath the membrane and vents it outside above the roofline.  This is sometimes referred to as a submembrane venting system. 

Another way to lower radon levels in a crawl space is to actively vent the entire crawl space with a fan.  This typically isn’t as effective as a submembrane system, and can be an issue with freezing pipes located in the crawl space in colder climates.

Parting Thoughts

I strongly feel as though radon gas is one of the most important things you should understand about your home.  It's prevalent in much of the country, and the evidence is solid that it can lead to lung cancer at certain levels.  A simple test of about $20 will tell you whether there is an issue that needs to be addressed.  

I've done a lot of research on this subject, and would be happy to answer any questions you may have in the comments section below.  I'd also be interested to hear what you've done in your home for mitigation, and whether it has been effective.